Most transfusion reactions are immediate.
There is one delayed reaction, called graft vs. host disease that includes a rash
. But it also includes fever
and, and would likely make you feel sick. If that's the case, you should call your doctor.
Otherwise, contact dermatitis
is a good guess.
Have you changed laundry detergents, or fabric softener, or dryer sheets, or soap or shampoo? Even a new deodorant or perfume could be causing a reaction.
The next time you get the rash, try to stop and backtrack, thinking about everything that came into contact with your skin -- and with your clothes.